If the authentication failure was due to a missing database, this extra
information can be logged. This will help cases where users are using
databases that do not exist.
If two or more session commands contain identical buffers, the buffer of
the first session command is shared between the others. This reduces the
amount of memory used to store repeated executions of session commands.
The purging of session command history in readwritesplit was replaced with
session command de-duplication. This was done to prevent problems that
could arise when the order of session commands plays a significant role.
The assertion that was added to RWSplitSession::handle_slave_is_target
failed when delayed_retry was enabled or when slave reconnection
occurred. In 2.3, targets returned by the target selection functions do
not need to be in use but they must be valid connection targets.
All executed session commands were logged in the RWSplitSession
destructor. This is not really necessary and shouldn't have been placed
there in the first place.
When the `optimistic_trx` mode is enabled, all transactions are started on
a slave server. If the client executes a query inside the transaction that
is not of a read-only nature, the transaction is rolled back and replayed
on the master.
The optimistic_trx parameter will control whether transactions are assumed
to be read-only and will be optimistically executed on slave
servers. Currently, the parameter does nothing.
Unconditionally update the previous target on each routed query. This
allows routing to the previous server in case it is needed. One example of
this is a new type of hint that allows routing to the same server where
the previous query was sent.
Also added a minor clarifying comment to the resetting of the
current_query.
Formatted readwritesplit with Astyle. Changed the initialization of
Backend::m_modutil_state to use curly braces to cope with Astyle's lack of
support for curly braces inside parentheses.
Readwritesplit now keeps track of how many read-only and read-write
transactions have been executed. This allows a coarse estimation of how
widely read-only transactions are done even without explicit read-only
transactions being used (i.e. START TRANSACTION READ ONLY).
Also change the following defaults:
- "selects": Was "verify_cacheable", is now "assume_cacheable"
- "cached_data": Was "shared", is now "thread_specific"
Readwritesplit would crash with the following transaction:
BEGIN;
SET @a = 1; -- This is where it would crash
COMMIT;
When a session command was a part of the transaction, empty queries
(i.e. NULL GWBUFs) would be added to the transaction. If the transaction
were to be replayed, MaxScale would crash when these NULL queries were
executed.
Once the empty responses were fixed, the replaying of the transaction
would fail with a checksum mismatch. This was caused by the wrong order of
processing in RWSplitSession::clientReply. The response processing for
session commands was done after the response processing for replayed
transactions. This would trigger a checksum comparison too early for the
transaction in question.
The command is saved in a function object which is read by the monitor
thread. This way, manual and automatic cluster modification commands are
ran in the same step of a monitor cycle.
This update required several modifications in related code.
The monitor now detects when a server has changed such that a replication
graph rebuild is needed and only then rebuilds the graph and detects
cycles and master.
Also, some old code is no longer called in the monitor cycle. It will be
removed in later commits. Refactored some of the related functions.
The id has now been moved from mxs::Worker to mxs::RoutingWorker
and the implications are felt in many places.
The primary need for the id was to be able to access worker specfic
data, maintained outside of a routing worker, when given a worker
(the id is used to index into an array). Slightly related to that
was the need to be able to iterate over all workers. That obviously
implies some kind of collection.
That causes all sorts of issues if there is a need for being able
to create and destroy a worker at runtime. With the id removed from
mxs::Worker all those issues are gone, and its perfectly ok to create
and destory mxs::Workers as needed.
Further, while there is a need to broadcast a particular message to
all _routing_ workers, it hardly makes sense to broadcast a particular
message too _all_ workers. Consequently, only routing workers are kept
in a collection and all static member functions dealing with all
workers (e.g. broadcast) have now been moved to mxs::RoutingWorker.
Now, instead of passing the id around we instead deal directly
with the worker pointer. Later the data in all those external arrays
will be moved into mxs::[Worker|RoutingWorker] so that worker related
data is maintained in exactly one place.
To get rid of the need that a Worker must have an id, we store
in the MXS_POLL_DATA structure a pointer to the owning worker
instead of the id of the owning worker. This also allows some
further cleanup as the need for switching back and forth between
the id and the worker disappears.
The id will be moved from Worker to RoutingWorker as there
currently is a fair amount of code that assumes that the id of
routing workers start from 0.
In case an array of cache rules is provided, we will only store
references to the objects in the array. Consequently, the counts of
the borrewed references to the objects must be increased, and the
reference count of the array itself decreased.
If a session command produces a different result on the slave than it did
on the master, a warning is logged. This warning now also logs the query
that was being executed to make investigation of the problem easier.
Previously schemarouter only mapped databases to the servers
they were resided on. Now all the tables are also mapped to allow the
router to route queries to the right server based on the tables used in
that query.
The only way to cleanly separate the maxutils library from the MaxScale
CMake project is to make it a standalone CMake project. With the help of
ExternalProject, it should be relatively easy to use.
Backend::execute_session_command would use the overridden write method
instead of the Backend::write method that it intended to use. This caused
session commands that did not expect a response to be in a state that
expected a result.
Also fixed RWBackend::write pass the response_type value to
Backend::write.
If the service user does not have adequate grants to the mysql tables, the
legacy query is used. This prevents an upgrade failure when the user was
lacking the new privileges.
The cache filter walks through the resultset in order to detect
when the resultset ends. That is, it reads each packet header as
they arrive.
In case the resultset is large, the cache will have to read several
packet headers. That it does using gwbuf_copy_data(). However, as that
was done using the first received GWBUF as the starting point, it meant
that in gwbuf_copy_data() the buffer chain was walked over and over
and over again, with a significant performance hit as the result.
Now we separetely store the last buffer received, and the the starting
offset of it. That way there will be no buffer chain walking.
As this is a common problem, GWBUF could cache the offset of the tail,
thus removing the performance penalty if you read from an offset that
happens to be in the tail. However, it's better to do that as a part
of a general overhaul of GWBUF.
If the server sends a server shutdown error, it is safe for readwritesplit
to ignore it. When the TCP connection is closed, the router error handling
will discard the connection, optionally replacing it.
The function implemented redundant functionality and replacement with
modutil_get_next_MySQL_packet was planned.
When faced with a packet header spread over multiple buffers, the packet
length calculation would read past the buffer end. This is fixed by taking
modutil_get_next_MySQL_packet into use.
Identical behavior to the old function is achieved by calling
gwbuf_make_contiguous for each packet to store them in a contiguous area
of memory. This should be either removed and only done when
RCAP_TYPE_CONTIGUOUS_INPUT is requested or be made an innate feature of
statement based routing.
This also applies to autoselect switchover. The disk space warning has the least
priority, as the other criteria could lead to replication failures. Also, print
the reason the new master was selected over the second best candidate.
